1. Diet and exercise boasters Those who tell you how far they've cycled, how fast they ran and how many pounds they've shed.

2. People who share pictures of every meal People who tell you about every meal are boring enough. These people, for reasons nobody can fathom, photograph it.

3. Cryptic status writers Some are mysterious: "I can't believe that just happened!" Others are passive aggressive: "Don't you hate it when people promise to do something and then let you down?" One thing's for sure - if you ask them what they're on about, they'll clam up.